Pushbutton door switch



` I March 26, 1968 R. F. scHABER PUSHBUTTON DOOR SWITCH Filed OCt. 22, 1965 NN Nm ww Il 3 Nm3@ f//Jl w r I' 'al Illu,

l 'IIIIIIII" INVENTOR. Fjcaey l Pa z2 'fmfw f United States Patent O 3,375,339 PUSHBUTTON DOOR SWITCH Ralph F. Schaber, Warren, Mich., assignor to Chrysler Corporation, Highland Park, Mich., a corporation of Delaware Filed Oct. 22, 1965, Ser. No. 501,022 1 Claim. (Cl. ZOO- 159) ABSTRACT OF THE DISCLOSURE A switch for automatically turning on one or more lights when a door is opened, or for energizing a signal lamp or the like when a control pedal or lever is operated. The switch has a spring loaded plunger which is disposed ior reciprocal movement in a tubular housing which housing provides a fixed contact surface. The movable contact element of the switch is carried by t-he plunger and the surface of the plunger is covered with a dielectric material so that the accumulation of Idirt or moisture within the space between the plunger and movable contact will not result in the establishment of Ia cu-rrent path therebetween. Accordingly, electrolytic decomposition of the switch contact is averted.

This invention relates generally to an electric switch and more particularly to an electric switch automatically actuated to a closed position in response to, for example, the movement of a cooperating member such as by the opening of an associated door.

Automotive vehicles have undergone substantial changes in both interior lighting and the means for controlling such lighting. In the past, only manually actuated electric switches were provided within the interior of the vehicle for closing the circuits energizing the interior lights .(often referred to as courtesy lights). This general arrangement has been improved by provi-ding spring actuated electric switches, usually located in a portion of the vehicle defining a door opening, which would be automatically actuated to a closed position whenever Ian associated door was moved toward open position. The provision of such automatically actuated light switches has proved to be a material -benet because proper lighting is always provided for a passenger whether entering or leaving the vehicle. However, even though such automatic switches have been an improvement, the switches nevertheless exhibit undesirable characteristics.

'One of the major problems of the prior art switches is the relatively rapid deterioration of the switch contacts. It has been discovered that such deterioration is primarily due to the electrolytic decomposition.

In most instances of automotive application the switches are mounted in a portion of the structure delining a vehicle door opening or door frame so that the asso-- ciated door can, when being opened or closed, engage the switch and either close or open the circuitry associated W-ith the switch. However, the placement of switches in such locations often exposes them to both dirt and moisture. IIt has been ,found that even a slight accumulati-ou of dirt, especially in the presence of water or even relatively high humidity, provides an electrically conductive path as between at least one of the switch contacts and another element of the switch which is at a dilferent electrical potential. As a consequence of the conductive path the said contact experiences electrolytic decomposition.

Accordingly, an object of this invention is to provide, in an automatically actuated electrical switch, means for preventing the establishment of an electrically conductive path as by the accumulation of dirt or moisture.

3,375,339 Patented Mar. 26, 1968 "ice Another more specilic object of this invention is to provide, in an automatically actuated electrical switch, insulating means for both electrically insulating one of the contacts from its supporting member and at the same time preventing lthe establishment of an electrically conductive path as by the accumulation of dirt or moisture.

Other more specic objects and advantages of this invention will become -apparent when reference is made to the following description an-d accompanying drawings wherein: f

'FIGURE l is a longitudinal cross-sectional view of an electric switch, constructed in accordance with this invention, and shown mounted in a fragmentary portion of a vehicular door frame; and

FIGURE 2 is a view, in cross-section, illustrating the switch of 'FIGUR-E l in an open position.

Referring now in greater detail to the drawings, FIG- URE 1 illustrates the electric switch 10, of the invention, as being suitably secured to a vehicular door frame portion 12 and electrically connected serially with a suitable lighting system, represented by a bulb 14, and a battery 16 by means of electrical conductors 18 and 20. Battery 16 is also suitably lgrounded as at 22 by means of an electrical conductor 24.

The switch assembly 10 is comprised of an externally threaded nut member 26, provided with a tool engaging portion 28, having an axially directed opening 30 formed therethrough for the reception of a generally tubular body 32. The tubular body 32 may be retained within nut 26 by any suitable means such as, for example, being pressed therein or having generally outwardly ared portions 34 and 36 which cooperate with enlarged opposite ends of the opening 30.

End 38 of body 32 is also .preferably formed to provide a generally radially inwardly directed tapered `or conical surface 40 which terminates in a radially directed annular ange por-tion 42. The annular flange portion 42 is also provided with an axially directed tubular or lip portion 44 yforming an opening 46 =for the reception therethrough of an actuating rod 48.

A coiled compression spring 50 is received within tubular lbody 32 generally about rod 48 so as to have one end abutting against the flange por-tion 42 (serving as a spring retainer) and the opposite end abutting against a head or striker portion S2 secured to and carried by one end of rod 48.

The actuating rod or plunger 48, which is axially movable relative to tubular body 32, carries at its end opposite to the head 52 a tubular contact member 54 which is illustrated as having a portion 56 of reduced cross-section for securing thereto an end of conductor 18. Nut 26, tubular body 34 and tubular contact 54 are metallic; further, because of structural requirements the rod 48 as well as the head 52 are also metallic. Therefore, an intermediate connecting member 58 of electrically non-conductive material is secured about the preferably knurled end 60 of rod 48 and situated within the enlarged opening 62 of contact member 54. Tabs 64 may be struck out of contact 54 and bent generally inwardly thereof in order to provide for retention ot insulator 58 within opening 62 and thereby assure an operative mechanical connection between rod 48 and contact 54.

As should be evident from FIGURE 1, the open end 66 of contact 56 provides a ring-like contacting surface for engagement with the conical contacting surface 40 of body 32 in order to complete an electrical circuit therethrough. Of course, nut 26 is suitably grounded as schematically illustrated at 68 by means of, for example, a metallic structural portion of the vehicle as the door frame 12. When the respective elements are in the positions shown in FIGURE 1 the electrical circuit through bulb 14 is of course completed. This would normally be the situation whenever the associated vehicle door was opened.

FIGURE 2 illustrates the opening of the electrical circuit as caused by the associated door, a portion of which is illustrated at 70, abuttingly engaging the head 52 and axially displacing actuating rod 48 and the contact 54 carried thereby. As the end 66 of contact 56 moves away from conical surface 40, the circuit is opened de-energizing the bulb 14. Prior art switches of this type employ an insulating member between the end 60 of plunger rod 48 and contact S4. However, the insulators thusly employed have terminated in a transverse end wall against which the tabs abutted. The annular space between the inner surface of contact 54 and the outer diameter of plunger rod 48 was provided in order to accommodate the generally conical configuration of contact surface 40.

In actual practice, switches of this type and purpose are relatively small and the radial clearance between the outer diameter of plunger rod 48 and the inner surface of contact 54 is often less than a sixteenth of an inch. As previously stated, the switch, and `particularly the area between contact 54 and rod 48, is susceptible to the accumulation of dirt and moisture. As a consequence thereof, a current path is often established between contact 54 and the portion of the rod 48 which is immediately radially inward thereof and not protected by any insulation.

Accordingly, the invention as herein disclosed contemplates the provision of an insulating member 58 which has a tubular extension 72, axially thereof, of an inner diameter 74 sufficiently large to tightly engage the outer diameter of rod 48. As will be noted by both FIGURES 1 and 2, insulator 58 is formed so as to provide suicient space for the acceptance of end 38. As best seen in FIGURE 2, the axial length Iof tubular extension 72 is of a magnitude suicient to permit end 76 to be disposed generally within the tubular body 32 when the door 70 has moved plunger 48 and contact 54 to its extreme open position.

In view of the above it is apparent that the accumulation of dirt or moisture within the space between the inner surface 78 of contact 54 and the outer diameter of tubular extension 72 will not result in the establishment of any current path between surface 78 and rod 48. Therefore, the tendency of electrolytic action to occur therebetween is averted.

Insulator 58 can, of course, be formed separately from rod 48 and then secured thereto, as by a press fit therebetween, or if desired, the insulator could be molded directly onto the rod 48.

Although only the preferred embodiment of the invention has been disclosed and described it is apparent that other embodiments and modifications of the invention are possible within the scope of the appended claim.

I claim:

1. A switch assembly comprising a tubular housing member having an end portion constituting a switch terminal, a plunger member slidably mounted in said tubular housing member for movement axially thereof, a conductor carrying member spaced from said plunger member, a connecting member formed of a non-conducting material connecting said plunger and said conductor carrying member, and spring means on said tubular housing member biasing said plunger to a circuit completing position in which the plunger projects out of one end of said tubular housing member and the conductor carrying member engages said terminal to complete a circuit through said switch assembly, said connecting member comprising a generally annular body engaging one end of said plunger and engaging and carrying said conductor carrying member, said plunger member being moveable in a second direction to move said conductor carrying member away from said terminal against the force of said spring, and said plunger having an electrically nonconducting surface of an axial length suflicient to extend into said tubular housing member throughout operative movement of the plunger so that a current path is precluded as between said conductor carrying member and said plunger thereby preventing electrolytic action therebetween as well as the passage of current from said conductor carrying member through said plunger to said tubular member, said electrically non-conducting surface of said plunger being ineffective to prevent electrolytic action between said conductor carrying member and said tubular housing member when said plunger is in said circuit completing position wtih said conductor carrying and tubular housing members in physical engagement.

References Cited UNITED STATES PATENTS 2,921,155 1/1960 Basso 200--61 3,115,559 12/1963 Cass et al 200--168 FOREIGN PATENTS 658,742 5/1963 Canada.

ROBERT K. SCHAEFER, Primary Examiner.

H. BURKS, Assistant Examiner. 

